Compared to the non-Sjögren cohort, the Sjögren cohort had a significantly higher risk of breast cancer occurring in the upper inner quadrant (HR: 3.256, 95% CI: 1.032–10.27) and estrogen receptor positivity (HR: 1.640, 95% CI: 1.014–2.653) in Model 4, in which comorbidities were added and medicine was used in combination with the previous propensity score matching. The gene discussed is ESR1; the disease is breast cancer.